curvature versus slope
  n = 86961 
  X=0, Y = 58.02 +/- 26.43 
  Weighted least-squares fit:  Y = 69.6 + 1.481 X  + -0.01644 X**2 

slope versus dZ, curvature < 5
  n = 33782 

  Weighted least-squares fit:  Y = 109.8 + -1.932 X  + 0.01457 X**2 
     at X = 100, Y = 62.3 
     Bad fit. P2 = 0
slope versus dZ, curvature < 15
  n = 59858 

  Weighted least-squares fit:  Y = 108.8 + -1.859 X  + 0.01401 X**2 

curvature versus dZ, slope < 10
  n = 1649 
  X=0, Y = 99.38 +/- 10.64 
  Weighted least-squares fit:  Y = 99.4 + -1.863 X  + 0.13747 X**2 


Number of samples 87566
Max dz = 900
Mean dz = 56
RMS dz = 126.031742034
100cm = 85.9682981979 percentile value of dz